The purpose of this proposal is to examine how motion as a naturally occurring stimulus pattern may induce visual cortical receptive field plasticity mediated by spike-timing-dependent plasticity (STDP). First, in vitro electrophysiology experiments will be conducted in slices of rat visual cortex to examine the effects of trains of spikes in inducing STDP. This experiment will reveal the dependence of synaptic plasticity on both the timing and number of spikes, which will aid in predicting the role of cortical direction selectivity in the induction of plasticity in vivo. The effects of direction selectivity on receptive field plasticity will then be measured in vivo in anesthetized cat using asynchronously flashed stimuli, and the results will be compared to the predictions of the experiments in slices. Finally, motion stimuli will be used in the cat experiments to determine if they can induce shifts in cortical receptive fields. The results of these experiments will help to strengthen the connection between synaptic plasticity and the functional changes seen in cortical networks. [unreadable] [unreadable]